PLASMA GONADOTROPHIN LEVELS IN OVULATORY AND ANOVULATORY PATIENTS

Summary Although episodes of FSH and LH secretion in four normal, fourteen anovulatory and one postmenopausal woman were confirmed by samples taken every 15 minutes for three hours, single plasma samples invariably provided a valid estimate of the current mean plasma FSH level, and of the current mean plasma LH level during the follicular phase of the ovulatory menstrual cycle and in anovulatory women with a mean plasma LH value of less than 0.8 mlU/ml. If the mean plasma LH value in anovulatory women exceeded 0.8 mlU/ml, the maximum difference between single and mean values was 28.3±4.7 per cent for four patients with oligomenorrhoea and 43.4±5.2 per cent for five patients with secondary amenorrhoea. Single plasma samples were collected from 26 patients with primary amenorrhoea, 95 patients with secondary amenorrhoea, 51 patients with oligomenorrhoea and 33 postmenopausal patients not on replacement therapy. In each group there were subjects with plasma FSH values in the postmenopausal range and they were unlikely to respond to ovulation induction. Those patients aside, plasma FSH values were similar in subjects with secondary amenorrhoea and oligomenorrhoea, but patients with oligomenorrhoea had significantly higher plasma LH values (p<0.001); mean levels of neither FSH nor LH showed a significant correlation with response to treatment with clomiphene but in patients with secondary amenorrhoea an ovulatory response to clomiphene did not occur unless the individual's plasma FSH value was in excess of 1.4 mlU/ml. In patients with oligomenorrhoea, plasma LH levels below 0.8 mlU/ml precluded successful treatment with clomiphene.